1. Field of the Invention
The present invention relates to a vehicle seat including a box-shaped upper frame (an upper framework of a seatback) having a hat-shaped section, and a holder (a member into which a headrest stay is inserted).
2. Description of Related Art
As this type of vehicle seat, there has been known a vehicle seat described in Chinese Utility Model Publication No. 2012-40297. In the vehicle seat, a seatback rises from a seat cushion, and a headrest is attached to an upper part of a seatback. On a bottom part of the headrest, a pair of headrest stays (in a bar shape) are provided at a given interval in a projecting manner. A back frame (a metal frame body) serving as a seatback framework includes an upper frame serving as an upper framework, and an active headrest device. The upper frame is a box-shaped member having a hat-shaped section (a rear side is opened), and is provided with paired elongated holes into which the headrest stays are insertable. Each of the elongated holes is a hole portion penetrating through the upper frame in an up-down direction, and is elongated in a seat front-rear direction (sliding of the headrest stays in the seat front-rear direction is allowed). Further, the active headrest device is a device configured to tilt the headrest stays in the seat front-rear direction, and is disposed in a back frame (below the upper frame). In the publicly known technique, the headrest is placed on an upper part of the back frame (in an upright state), and then, each of the headrest stays is inserted into each of the elongated holes so as to be connected to the active headrest device. At the time of a rear collision of a vehicle, the active headrest device is driven to tilt the headrest stays forward (to slide the headrest stays in the elongated holes), thereby making it possible to move the headrest to an occupant-head side.